From 6a329eb853d177a8ba608d3503f394b906e9e6a8 Mon Sep 17 00:00:00 2001
From: Prachotan Bathi <prachotan.bathi@arm.com>
Date: Tue, 1 Jul 2025 11:28:58 -0500
Subject: [PATCH] ArmPlatformPkg: Capture TransferList Information for SEC

Capture TransferList address from register x3
Refer to section 3 of the FW Handoff Specification
https://firmwarehandoff.github.io/firmware_handoff
The TransferList header is present at the base address
captured by this variable.
For platforms with no TransferList support,
boot continues without any errors.

Signed-off-by: Prachotan Bathi <prachotan.bathi@arm.com>
---
 ArmPlatformPkg/Sec/AArch64/ModuleEntryPoint.S | 16 ++++++++++-
 ArmPlatformPkg/Sec/Sec.c                      | 27 ++++++++++++++++---
 ArmPlatformPkg/Sec/Sec.h                      |  1 +
 ArmPlatformPkg/Sec/Sec.inf                    |  1 +
 4 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/ArmPlatformPkg/Sec/AArch64/ModuleEntryPoint.S b/ArmPlatformPkg/Sec/AArch64/ModuleEntryPoint.S
index 154be1111d..28cd015772 100644
--- a/ArmPlatformPkg/Sec/AArch64/ModuleEntryPoint.S
+++ b/ArmPlatformPkg/Sec/AArch64/ModuleEntryPoint.S
@@ -8,6 +8,19 @@
 #include <AsmMacroLib.h>
 
 ASM_FUNC(_ModuleEntryPoint)
+  // Check if register assignment at handoff matches spec
+  MOV64 (x4, 0x14a0fb10b)
+  // Check if x1 holds TransferList signature
+  cmp   x1, x4
+  b.ne  _SkipTransferList
+
+  // Skip TransferList init if x2 is not equal to 0
+  cbnz  x2, _SkipTransferList
+
+  // Set the TransferList Base Address from register x3
+  mov   x10, x3
+
+_SkipTransferList:
   // Do early platform specific actions
   bl    ASM_PFX(ArmPlatformPeiBootAction)
 
@@ -47,7 +60,8 @@ ASM_PFX(MainEntryPoint):
   // The PEI Core Entry Point has been computed by GenFV and stored in the second entry of the Reset Vector
   MOV64 (x2, FixedPcdGet64(PcdFvBaseAddress))
   ldr   x0, [x2, #8]
-
+  // Pass the TransferList Base Address
+  mov   x1, x10
   // Move sec startup address into a data register
   // Ensure we're jumping to FV version of the code (not boot remapped alias)
   ldr   x3, =ASM_PFX(CEntryPoint)
diff --git a/ArmPlatformPkg/Sec/Sec.c b/ArmPlatformPkg/Sec/Sec.c
index 4535ae7e78..0e9d1c82fe 100644
--- a/ArmPlatformPkg/Sec/Sec.c
+++ b/ArmPlatformPkg/Sec/Sec.c
@@ -151,12 +151,15 @@ PrintFirmwareVersion (
 
   @param[in]  PeiCoreEntryPoint   Address in ram of the entrypoint of the PEI
                                   core
+  @param[in]  TransferListBaseAddr Address of the Transfer List base address
+
 **/
 STATIC
 VOID
 EFIAPI
 SecMain (
-  IN  EFI_PEI_CORE_ENTRY_POINT  PeiCoreEntryPoint
+  IN  EFI_PEI_CORE_ENTRY_POINT  PeiCoreEntryPoint,
+  IN  UINTN                     TransferListBaseAddr
   )
 {
   EFI_SEC_PEI_HAND_OFF    SecCoreData;
@@ -164,6 +167,21 @@ SecMain (
   EFI_PEI_PPI_DESCRIPTOR  *PpiList;
   UINTN                   TemporaryRamBase;
   UINTN                   TemporaryRamSize;
+  VOID                    *TransferListBase;
+
+  // Dump the Transfer List
+  TransferListBase = (VOID *)TransferListBaseAddr;
+  if (TransferListBase != NULL) {
+    if (TransferListCheckHeader (TransferListBase) != TRANSFER_LIST_OPS_INVALID) {
+      DEBUG_CODE_BEGIN ();
+      TransferListDump (TransferListBase);
+      DEBUG_CODE_END ();
+    } else {
+      DEBUG ((DEBUG_ERROR, "%a: No valid operations possible on TransferList found @ 0x%p\n", __func__, TransferListBase));
+    }
+  } else {
+    DEBUG ((DEBUG_INFO, "%a: No TransferList found, continuing boot\n", __func__));
+  }
 
   CreatePpiList (&PpiListSize, &PpiList);
 
@@ -197,10 +215,13 @@ SecMain (
 
   @param[in]  PeiCoreEntryPoint   Address in ram of the entrypoint of the PEI
                                   core
+  @param[in]  TransferListBaseAddr Address of the Transfer List base address
+
 **/
 VOID
 CEntryPoint (
-  IN  EFI_PEI_CORE_ENTRY_POINT  PeiCoreEntryPoint
+  IN  EFI_PEI_CORE_ENTRY_POINT  PeiCoreEntryPoint,
+  IN  UINTN                     TransferListBaseAddr
   )
 {
   if (!ArmMmuEnabled ()) {
@@ -237,7 +258,7 @@ CEntryPoint (
   ArmPlatformInitialize (ArmReadMpidr ());
 
   // Goto primary Main.
-  SecMain (PeiCoreEntryPoint);
+  SecMain (PeiCoreEntryPoint, TransferListBaseAddr);
 
   // PEI Core should always load and never return
   ASSERT (FALSE);
diff --git a/ArmPlatformPkg/Sec/Sec.h b/ArmPlatformPkg/Sec/Sec.h
index 56d9f352bd..c1cd10d909 100644
--- a/ArmPlatformPkg/Sec/Sec.h
+++ b/ArmPlatformPkg/Sec/Sec.h
@@ -23,6 +23,7 @@
 #include <Library/SerialPortLib.h>
 
 #include <Ppi/TemporaryRamSupport.h>
+#include <Library/ArmTransferListLib.h>
 
 /**
   Helper function to switch to a different stack. Implemented in assembler as
diff --git a/ArmPlatformPkg/Sec/Sec.inf b/ArmPlatformPkg/Sec/Sec.inf
index a75ce8d5ec..2d1622cf52 100644
--- a/ArmPlatformPkg/Sec/Sec.inf
+++ b/ArmPlatformPkg/Sec/Sec.inf
@@ -48,6 +48,7 @@
   PrintLib
   SerialPortLib
   StackCheckLib
+  ArmTransferListLib
 
 [Ppis]
   gEfiTemporaryRamSupportPpiGuid